fix: stabilize portfolio scrolling and loading

Remove skeleton swaps and deferred layout estimates, restore reveal state, and use native proximity scrolling for project cards. Also make the Docker build npm registry configurable.

src/components/MilestonesSection.tsx

@@ -1,4 +1,4 @@
-import { ImageWithSkeleton } from './ImageWithSkeleton';
+import Image from 'next/image';
 import { ExternalLink } from 'lucide-react';
 import { getMilestones } from '@/data/milestones';
 import { messagesByLocale, type Locale } from '@/i18n/content';
@@ -10,7 +10,7 @@ export const MilestonesSection = ({ locale }: { locale: Locale }) => {
   const copy = messagesByLocale[locale].milestones;
 
   return (
-    <section id="milestones" className={styles.milestonesSection} data-deferred-render data-looping-motion>
+    <section id="milestones" className={styles.milestonesSection}>
       <div className="content-container">
         {/* Section Header */}
         <div className="section-header" data-reveal="soft">
@@ -27,13 +27,12 @@ export const MilestonesSection = ({ locale }: { locale: Locale }) => {
             <div key={item.id} className={styles.certCard}>
               {/* Thumbnail */}
               <div className={styles.thumbnailContainer} data-reveal="image">
-                <ImageWithSkeleton
+                <Image
                   src={item.image.src}
                   alt={item.title}
                   fill
                   sizes="(max-width: 650px) calc(100vw - 3rem), (max-width: 1024px) 44vw, 520px"
                   className={styles.certImage}
-                  skeletonShape="rounded"
                 />
               </div>